1. Field of the Invention
The present invention relates to a semiconductor assembly for an improved three-dimensional integrated circuit structure, and more particularly, to a semiconductor assembly having a stacked module structure employing a heat sink and a capacitor plate.
2. Description of Related Art
Three-dimensional packaging technology has become useful in electronic systems needing larger capacity, faster operating speed, and minimized size. Previously proposed three-dimensional packaging technologies include chip-stacked type and assembly-stacked type. Almost all assembly manufacturers utilize configurations for reducing device size in order to enhance operating speed and to increase capacity. However, the chip-stacked package, when implemented, has low reliability, high cost, and a long developing period. The assembly-stacked package still has disadvantages compared with a two-dimensional packaging configuration. It requires process steps for vertical interconnection in addition to the basic packaging process for a semiconductor assembly. It also requires mounting a heat sink on each semiconductor assembly using an additional process step, or employing a separate cooling device for heat emission. Each heat sink on each assembly increases the volume of the stacked package when implemented and also makes high density packaging impossible. If the cooling device is employed, the cost for manufacturing the assembly-stacked package is increased.
FIG. 1 illustrates a conventional assembly-stacked package disclosed in an article titled "3-D Stacked Memory Devices Using a Proprietary Process" proposed by STAKTEK CO. Leads 12 protruding from assemblies 11 are electrically connected to a connecter 13 after the assemblies 11 have been stacked atop each other. Then, for heat emission, thin metal foil portions are stacked between the assemblies 11, or, as shown in FIG. 1., a grounded heat sink 14 is formed to cover the overall stacked structure.
However, the formation of the thin metal foil portions and the need for protruding die pad regions at the top of the structure make the fabrication process more complicated. Moreover, the packaging configuration of FIG. 1 is a difficult to use with further structures with a core as a carrier for interconnecting between the assemblies 11. Also, this configuration is not well-suited to mass-production since it is not generally compatible used with existing manufacturing apparatuses.
A technique proposed in U.S. Pat. No. 5,105,261, as illustrated in FIG. 2A, involves a three-dimensional assembly-stacked structure in which bilateral leads 22 protruding from assemblies 21 are folded in a gull-wing shape. The leads 22 are inserted into pin holes 26 on two printed circuit boards 23 that are inserted into connection sockets 25. The folded leads 22, as shown in FIG. 2B, extend through the pin holes 26 and are attached to the printed circuit boards 23 by solder 24. The disclosed device, however, has several topological limitations such that it is difficult to increase the packing density due the height of the device. It is also difficult to increase the number of the assemblies which can be stacked therein. Furthermore, the attaching portions between the assemblies and the printed circuit boards are connected only by the bonding force of the solder, which can be structurally weak.
A single in-line memory module developed by RTB Co., as shown in FIG. 3, includes a plurality of assemblies 31, each having a plurality of leads 32. Each lead 32 has a pin hole connecting the lead 32 to a corresponding vertical lead 36. A plurality of pins 35 extend between a bottom plate 34 and a top plate 33 and pass through the pin holes of leads 32, so that the leads 32 are fixed thereto and supported by the pins 35. The top plate 33 has a plurality of grooves (not shown) to engage the pins 35, which also protrude under the bottom plate 34 for mounting on a printing circuit board (not shown). (Pins 35 are not all shown for clarity.)
In accordance with the conventional single in-line memory module shown in FIG. 3, since the number of pins may increase if the pitch between the leads becomes narrow, it is difficult to mount the module with such thin pins on the printed circuit board without a specific socket for connecting the pins thereto. Furthermore, the vertical interconnection between fine leads and thin pins makes the structure and its fabricating process complicated, thereby limiting packing and stacking capacity.